[FOM] Question about theoretical physics

Joe Shipman JoeShipman at aol.com
Wed Mar 6 12:10:18 EST 2013

There must be a book which explains the details, otherwise how does anyone learn how to do this?

What you have said makes the situation seem much more unsatisfactory.

-- JS

Sent from my iPhone

On Mar 6, 2013, at 3:00 AM, Arnold Neumaier <Arnold.Neumaier at univie.ac.at> wrote:

On 03/02/2013 07:57 PM, Joe Shipman wrote:

> Can Professor Neumaier, or any other theoretical physicist, provide a link the following much simpler pieces of documentation?
> 1) a method for enumerating Feynman diagrams relevant to the calculation of the magnetic moment of the electron

This is not how it is done. The actual high order computations involve an expansion in powers of both alpha and 1/c^2, and the choice of the temrs evaluated is based on heuristics which ones are likely to influence the result. The actual method used is NRQED, not the standard Feynman series expansion. Figuring out what precicesly has been done or needs to be done to replicate the results is itself a research project that only those are interested to do who actually want to do the checking (usually because they have an alternative in mind that might work better).

> 2) a high-level description of the process by which the value of a Feynman integral for *one specific nontrivial Feynman diagram* is numerically approximated

The contribution of a single Feynman integral is infinite, except for the lowest order (zero loop) tree level disarams. Finite values arise form linear combinations of such contributions that have a definite finite value in the renormalization limit.

The closest approximation to what you want is in the work by Kreiner, but this is itself quite abstract (involving Hopf algebras) and acccessible only to a small part of theretical physicists.

Arnold Neumaier

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